<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>07_相对定位</title>
    <style>
        .fu{
          background-color: #ff0;
        }
        .fu>div{
          width: 100px;
          height: 100px;
        }
        .z1{
          background-color: #f00;
        }
        .z2{
          background-color: #0f0;
            /*固定定位：会脱离文档流且释放文档流，一直都是html*/
            position: fixed;
            left: 0;
            bottom: 0;
        }
        .z3{
          background-color: #00f;
        }
    </style>
</head>
<body>
<div class="fu">
  <div class="z1"></div>
  <div class="z2"></div>
  <div class="z3"></div>
</div>
</body>
</html>